1. Field of the Invention
This invention relates to three-wheeled vehicles, and more particularly to improved, high-efficiency, front-wheel drive tricycles of a "2-1" (1 front-2 rear) configuration with an independent rear suspension having a transfer gear/disc braking system and a fully engineered front end that is particularly suitable for human-powered operation with the driver in the recumbent, supine position. In a most preferred embodiment, the improved tricycle of this invention is fully faired. Alternatively, the vehicle is adaptable to be used with a small displacement engine providing mileage on the order of several hundred miles per gallon. In still other embodiments, a partially faired or unfaired vehicle is particularly suitable for Third World transportation, light haulage, industrial and agricultural usage.
2. General Background
Cycles, particularly bicycles, have been the subject of continuous engineering development from the days of the two-wheeled push bike in 1816 by Baron von Drais in Karlsruhe, Germany, with his "lauf maschine" (also known as the Draisine machine) to the first pedal-operated bike by Scotsman Kirkpatrick MacMillan in 1839, Pierre Lallement's "boneshaker", a crank bicycle of the 1860's, to today's high-tech racing bikes. The mechanical system of the bicycle, that is, the pedal, crank and chain transfer system to the rear wheel gears has been estimated to be 92-95% efficient in transferring energy from the human operator to the rear wheel. However, at speeds of 25 miles an hour and above, 90% of the effort goes into overcoming wind resistance. This is due in principal part to the upright position of the rider.
Tricycles have enjoyed much less popularity for the principal reasons that they are heavier by the addition of a third wheel, and their width offers even greater wind resistance. Nor do they have the advantages of good handling characteristics evidenced by bicycles in which the rider can maneuver easily with the front fork steering and the ability of the rider to lean into turns.
There have been some traditional usages of tricycles, most commonly in the West as children's play vehicles. Rear wheel drive three-wheeled pedicabs or bicycle-powered rickshaws are in extensive use in other areas of the world, particularly the Orient. Typically, such pedicabs consist of the front half of a bicycle including the single front wheel and fork mount with the rider in the upright position, with two trailing wheels between which are mounted seats for passengers or platforms or racks for light haulage. These are "1-2" (1 front 2 rear) configurations.
More recently, with the advent of high technical interest in breaking speed records for human-powered vehicles (HPVs), there has been a renewed interest in faired tricycles. This has come about at least in part by the need to reduce the cross-sectional area to reduce wind resistance. Accordingly, the rider position has been changed to a recumbent or semi-recumbent position, either prone or supine. Although there have been several bicycles through the years with recumbent positions, most recently the HYPERCYCLE, the EASY RACER, and the AVATAR 2000, these bicycles have proven to be difficult to ride because because it is more difficult to balance the bicycle in the recumbent position, particularly the supine position. Those three recent bicycles are reminiscent of the 1934 era GRUBB recumbent bicycle and the Ravat CYCLORATIO patented in England in 1936 by Albert Raymond.
Because of the balance problem of recumbent cycles, a tricycle of "2-1" format has been used for speed challenge HPVs, including the current world speed record holding Vector tricycle. The Vectors are steerable only about 10.degree.-15.degree. from a straight line as the speed is determined over a 200-yard, straight-line course.
3. Description of the Prior Art
In the relevant tricycle art, in addition to the well-known child's tricycles and the pedicab or bicycle-powered rickshaw, all of which are single wheel in the front with two rear wheels ("1-2" types), there are a number of more recent developments. Both the child's tricycle and the pedicab/bike-drawn rickshaw employ front-fork, single-wheel steering. The pedicabs and rickshaws are rear-wheel driven, while the child's tricycle is front-wheel driven by does not employ a gear system. The CONKLING recumbent tricycle employed a single rear wheel with rear-wheel drive. The front steering employed a pair of standard bicycle head tubes and front forks joined together with a transverse bar or tube. The frame was hung from the crossbar between the front pair of standard bicycle head tubes and fork arrangement, Ecomotion, No. 4, 10/81, pages 5 and 6.
The proposed GILMORE pedal car (as shown in Ecomotion 3/80, page 3) calls for the rider being in the prone position with the tricycle having dual front-wheel drive with rear steering.
The recently developed VECTOR, as shown in the Sept. 1981 American Wheelman, is a fully faired tricycle having two large wheels in the front and one in the rear (2-1 type). The front track is very narrow, and the vehicle has a steering displacement of only about 15.degree. each side of centerline. The rider is in a recumbent supine position with the bottom bracket being well above the rider's hip joint. The steering is by means of a tiller. The vehicle has a very large 100-tooth front gear, and the chain extends back to a rear-wheel drive gear cluster providing 6 speeds. There is braking only at the rear wheel. This is a race vehicle only, is not intended for street use, and comes in a single-rider vehicle and a tandem in which the two riders are back to back. Drag coefficient is said to be 0.11, and drag is reported to be reduced on the order of 75%. The VECTOR holds the world records for a single-rider, 200-meter sprint at 58.64 miles per hour, and 62.92 miles per hour for a tandem, both achieved at the International Human Powered Vehicle Association (IHPVA) championships held in California in 1980.
More recently, in an effort to develop more practical road vehicles, the IHPVA began holding road races which tested stability, endurance and cornering in addition to raw, straight-line speed. As reported in the September 1981 American Wheelman, page 4:
"According to Paul Van Valkenburgh, a race car engineer and designer, `the practical possibility for any of the HPV's we saw racing is really slim except on a bike path. If you haven't ridden them, you don't know how vulnerable you feel. Your visibility is bad. Your conspicuity is bad, and the protection is minimal. Even Al Voigt, who builds the Vectors, is reluctant to make demonstration runs for his vehicle on the street, even when he's got an escort, because you've got half the visibility of a bicycle. PA1 `On a bicycle you're invisible. If you've got half the area, especially half the height, you're really invisible.`" PA1 "Paul B. MacCready, IHPVA timekeeper and well-known as the designer of human-powered and solar-powered airplanes states, `The Vector and similar vehicles are beautifully engineered for the purpose of winning a race. But now there is another goal--making a practical street vehicle. You don't do it by extrapolating from these vehicles. You do it by setting a goal, and building a thing that is going to do that. It may not even look like any of the vehicles here. It may not use bicycle wheels, standard sprockets or chains or whatever. PA1 `You've got to start with the practical goal--inexpensive, safe transportaton at commuting speeds, which I call 35 miles per hour less, not the freeway speeds.`" PA1 "It is a fact that dual steering wheels can never be made to track correctly and that one or both will be forced to skid sideways a little, especially on sharper turns. In an automobile, this is insignificant, but in a man-powered vehicle, this results in unnecessary extra friction and driving effort." PA1 "Disadvantages of this design, as I see it, are the need for relatively heavy front axle and a differential, and with a supine seating position, to get reasonable traction, the rider would have to straddle the front axle, thus would have to sit higher than with, for instance, a single driving wheel in the rear. PA1 "The one front drive, dual front wheel tricycle that I know of that has been completed was that of then Massachusetts Institute of Technology student Lee Laiterman. It was designed as a pedal-powered lawnmower. Minus the mowing attachment, Laiterman told me in a telephone conversation that it worked very well."
The same article "How About One for the Road?" on page 3 of the September 1981 American Wheelman states:
Another recent design is the AERO tricycle shown in the September 1981 American Wheelman. This is a rear-wheel drive tricycle having two front wheels smaller than the rear wheel. This tricycle employes a T-bar frame with tiller steering in which the wheels track parallel. The drive system is a rod linkage reciprocating system rather than a rotary pedaling of a standard bicycle. There is no rear suspension, and the driver's hip pivot is well above the crank pivot. This tricycle is not good for hill climbing because the rider cannot stand up on the pedals. The MATRIX is another racing 2-1 tricycle with two large front wheels that is apparently rear-wheel drive, fully faired with limited steering capability. The bottom bracket appears to be well above the rider's hip pivot. Similarly, the RED SHIFT also shown in the American Wheelman, September 1981, is a three-wheel vehicle of a 2-1 type but it is rear-wheel drive. The front wheels track parallel for racing in a straight line, and the pedals and the crank are behind and above the front axle. While this is a recumbent position, the bottom bracket is apparently well above the hip pivot.
A review of tricycles appeared in Ecomotion, No. 1, August 1979, in an article on "Tricycles" by Mike Eliasohn. He discussed the various types, including: single front wheel, rear drive (1S-2D); dual front wheels, rear drive (2-1D); and dual front wheels, front drive (2D-1). As to the latter, he states, "Such a design would use rear wheel steering, the same as on Buckminister Fuller's Dymaxion cars of the 1930's" (i.e., 2D-1S). He in turn quotes the editor of the Ecomotion Newsletter, Randy Gilmore, as stating about the theoretical advantages of the dual front-wheel, front-drive type of tricycle:
He also comments that the rear-wheel steering design has the advantage, since it is pulled rather than pushed, of being less tendency to scrub sideways on a sudden or sharp higher-speed turn. Eliasohn continues by commenting:
As to U.S. patents, U.S. Pat. No. 3,913,929 of Matsuura, which appears to be the basis of a rear-wheel drive tricycle called the "SLINGSHOT" by MASA, which is no longer made, shows a dual front-wheel, rear-wheel drive tricycle. The front wheels are steered in parallel, and the rear wheel is larger than the front wheels. The rider is slung between a pair of side frames, and steering is by means of levers, with one arm bent and the hands at knee level. The driving crank system is between the side frames and behind the front wheels. There are no springs, and the seat sling can be canvas, plastic or metal. Braking is by a friction braking to the wheel rims, a brake drum, or brake discs at the wheels. This is 2S-1D format.
The U.S. Patent to Hopkins U.S. Pat. No. 4,198,072 shows a tricycle having a single-driven front wheel with a crank and bottom bracket on an outrigger ahead of the front wheel. In this tricycle, the two rear wheels are extremely small, being on the order of the size of casters or skateboard-type wheels, which wheels are steerable by handlebars positioned below the seat. The handlebars are directly attached to the wheels, and the pivot is behind the back of the rider. This is a sports type of device for smooth, paved areas. It employs a pivoted fabric or mesh seat, the pivoting of which changes the steering axis. By shifting the steering axis depending on the position of the rider and leaning into the turns, a very exciting recreational ride is claimed. This is 1D-2S format.
The U.S. Pat. No. 4,272,095 of Ptaszek shows a child's tricycle with a single large front wheel on a fork which is direct drive through a crank forming the front-wheel axle. The two rear wheels are castered. The backrest of the seat is pivoted so that the caster angle can change. When the casters are perpendicular to the ground, the casters can whip, and the child does a spinout. This is 1DS-2T (turnable) format.
A toy auto is shown in the Doak U.S. Pat. No. 2,501,035. This is a tricycle having a sheel in the form of a convertible automobile. The front wheels are directly driven by a crank forming the wheel axle, and the rear wheel is steerable by a rod linkage system. This is 2D-1S format.
The McCormick U.S. Pat. No. 1,196,129 is a hand-powered quadracycle employing two large front wheels which are directly driven by a hand crank forming their axle, and a pair of smaller rear wheels carries a seat. The frame is articulated at approximately the knee position of the driver. Steering is done by warping the baseboard by foot pressure. This is 2DS-2A (articulated) format.